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Meat is animal tissue, often
muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...
, that is eaten as food. Humans have hunted and farmed other animals for meat since prehistory. The
Neolithic Revolution The Neolithic Revolution, also known as the First Agricultural Revolution, was the wide-scale transition of many human cultures during the Neolithic period in Afro-Eurasia from a lifestyle of hunter-gatherer, hunting and gathering to one of a ...
allowed the
domestication of vertebrates The domestication of vertebrates is the mutual relationship between vertebrate animals, including birds and mammals, and the humans who influence their care and reproduction. Charles Darwin recognized a small number of traits that made domestica ...
, including
chicken The chicken (''Gallus gallus domesticus'') is a domesticated subspecies of the red junglefowl (''Gallus gallus''), originally native to Southeast Asia. It was first domesticated around 8,000 years ago and is now one of the most common and w ...
s,
sheep Sheep (: sheep) or domestic sheep (''Ovis aries'') are a domesticated, ruminant mammal typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to d ...
,
goat The goat or domestic goat (''Capra hircus'') is a species of Caprinae, goat-antelope that is mostly kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the ...
s,
pig The pig (''Sus domesticus''), also called swine (: swine) or hog, is an omnivorous, domesticated, even-toed, hoofed mammal. It is named the domestic pig when distinguishing it from other members of the genus '' Sus''. Some authorities cons ...
s,
horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...
s, and
cattle Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...
, starting around 11,000 years ago. Since then,
selective breeding Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant m ...
has enabled farmers to produce meat with the qualities desired by producers and consumers. Meat is mainly composed of water, protein, and fat. Its quality is affected by many factors, including the genetics, health, and nutritional status of the animal involved. Without preservation, bacteria and fungi decompose and spoil unprocessed meat within hours or days. Meat is edible raw, but it is mostly eaten cooked, such as by
stewing A stew is a combination of solid food ingredients that have been cooked in liquid and served in the resultant gravy. Ingredients can include any combination of vegetables and may include meat, especially tougher meats suitable for slow-cooking, ...
or
roasting Roasting is a cooking method that uses dry heat where hot air covers the food, cooking it evenly on all sides with temperatures of at least from an open flame, oven, or other heat source. Roasting can enhance the flavor through caramelizat ...
, or processed, such as by
smoking Smoking is a practice in which a substance is combusted, and the resulting smoke is typically inhaled to be tasted and absorbed into the bloodstream of a person. Most commonly, the substance used is the dried leaves of the tobacco plant, whi ...
or salting. The consumption of meat (especially
red Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–750 nanometres. It is a primary color in the RGB color model and a seconda ...
and processed meat, as opposed to
fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...
and
poultry Poultry () are domesticated birds kept by humans for the purpose of harvesting animal products such as meat, Eggs as food, eggs or feathers. The practice of animal husbandry, raising poultry is known as poultry farming. These birds are most typ ...
) increases the risk of certain negative health outcomes including cancer,
coronary heart disease Coronary artery disease (CAD), also called coronary heart disease (CHD), or ischemic heart disease (IHD), is a type of cardiovascular disease, heart disease involving Ischemia, the reduction of blood flow to the cardiac muscle due to a build-up ...
, and
diabetes Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...
. Meat production is a major contributor to
environmental issues Environmental issues are disruptions in the usual function of ecosystems. Further, these issues can be caused by humans (human impact on the environment) or they can be natural. These issues are considered serious when the ecosystem cannot recov ...
including
global warming Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...
, pollution, and
biodiversity loss Biodiversity loss happens when plant or animal species disappear completely from Earth (extinction) or when there is a decrease or disappearance of species in a specific area. Biodiversity loss means that there is a reduction in Biodiversity, b ...
, at local and global scales, but meat is important to economies and cultures around the world. Some people (
vegetarians Vegetarianism is the practice of abstaining from the consumption of meat (red meat, poultry, seafood, insects, and the flesh of any other animal). It may also include abstaining from eating all by-products of animal slaughter. A person who pra ...
and
vegans Veganism is the practice of abstaining from the use of animal products and the consumption of animal source foods, and an associated philosophy that rejects the commodity status of animals. A person who practices veganism is known as a vega ...
) choose not to eat meat for
ethical Ethics is the philosophical study of moral phenomena. Also called moral philosophy, it investigates normative questions about what people ought to do or which behavior is morally right. Its main branches include normative ethics, applied e ...
, environmental, health or religious reasons.


Etymology

The word ''meat'' comes from the
Old English Old English ( or , or ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the Early Middle Ages. It developed from the languages brought to Great Britain by Anglo-S ...
word , meaning food in general. In modern usage, ''meat'' primarily means
skeletal muscle Skeletal muscle (commonly referred to as muscle) is one of the three types of vertebrate muscle tissue, the others being cardiac muscle and smooth muscle. They are part of the somatic nervous system, voluntary muscular system and typically are a ...
with its associated fat and connective tissue, but it can include
offal Offal (), also called variety meats, pluck or organ meats, is the internal organ (anatomy), organs of a butchered animal. Offal may also refer to the by-products of Milling (grinding), milled grains, such as corn or wheat. Some cultures strong ...
, other edible organs such as
liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...
and
kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...
. The term is sometimes used in a more restrictive sense to mean the flesh of
mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
ian species (pigs, cattle, sheep, goats, etc.) raised and prepared for human consumption, to the exclusion of
fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...
, other seafood,
insects Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...
, poultry, or other animals.


History


Domestication

Paleontological Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...
evidence suggests that meat constituted a substantial proportion of the diet of the earliest humans. Early
hunter-gatherer A hunter-gatherer or forager is a human living in a community, or according to an ancestrally derived Lifestyle, lifestyle, in which most or all food is obtained by foraging, that is, by gathering food from local naturally occurring sources, esp ...
s depended on the organized hunting of large animals such as
bison A bison (: bison) is a large bovine in the genus ''Bison'' (from Greek, meaning 'wild ox') within the tribe Bovini. Two extant taxon, extant and numerous extinction, extinct species are recognised. Of the two surviving species, the American ...
and
deer A deer (: deer) or true deer is a hoofed ruminant ungulate of the family Cervidae (informally the deer family). Cervidae is divided into subfamilies Cervinae (which includes, among others, muntjac, elk (wapiti), red deer, and fallow deer) ...
. Animals were
domesticated Domestication is a multi-generational mutualistic relationship in which an animal species, such as humans or leafcutter ants, takes over control and care of another species, such as sheep or fungi, to obtain from them a steady supply of reso ...
in the
Neolithic The Neolithic or New Stone Age (from Ancient Greek, Greek 'new' and 'stone') is an archaeological period, the final division of the Stone Age in Mesopotamia, Asia, Europe and Africa (c. 10,000 BCE to c. 2,000 BCE). It saw the Neolithic Revo ...
, enabling the systematic production of meat and the
breeding Breeding is sexual reproduction that produces offspring, usually animals or plants. It can only occur between a male and a female animal or plant. Breeding may refer to: * Animal husbandry, through selected specimens such as dogs, horses, and rab ...
of animals to improve meat production.


Intensive animal farming

In the
postwar period A post-war or postwar period is the interval immediately following the end of a war. The term usually refers to a varying period of time after World War II, which ended in 1945. A post-war period can become an interwar period or interbellum, w ...
, governments gave farmers guaranteed prices to increase animal production. The effect was to raise output at the cost of increased inputs such as of animal feed and veterinary medicines, as well as of animal disease and environmental pollution. In 1966, the United States, the United Kingdom and other industrialized nations, began factory farming of beef and dairy cattle and domestic pigs. Intensive animal farming became globalized in the later years of the 20th century, replacing traditional stock rearing in countries around the world. In 1990 intensive animal farming accounted for 30% of world meat production and by 2005, this had risen to 40%.


Selective breeding

Modern agriculture employs techniques such as
progeny testing Progeny may refer to: *A genetic descendant or offspring * Progeny Linux Systems, a defunct company which provided Linux platform technology * ''Progeny'' (Stargate Atlantis), an episode of the television series ''Stargate Atlantis'' *"Progeny", a ...
to speed
selective breeding Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant m ...
, allowing the rapid acquisition of the qualities desired by meat producers. For instance, in the wake of well-publicized health concerns associated with
saturated fat A saturated fat is a type of fat in which the fatty acid chains have all single bonds between the carbon atoms. A fat known as a glyceride is made of two kinds of smaller molecules: a short glycerol backbone, and fatty acids that each cont ...
s in the 1980s, the fat content of United Kingdom beef, pork and lamb fell from 20–26 percent to 4–8 percent within a few decades, due to both selective breeding for leanness and changed methods of butchery. Methods of
genetic engineering Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of Genetic engineering techniques, technologies used to change the genet ...
that could improve the meat-producing qualities of animals are becoming available. Meat production continues to be shaped by the demands of customers. The trend towards selling meat in pre-packaged cuts has increased the demand for larger breeds of cattle, better suited to producing such cuts. Animals not previously exploited for their meat are now being farmed, including mammals such as
antelope The term antelope refers to numerous extant or recently extinct species of the ruminant artiodactyl family Bovidae that are indigenous to most of Africa, India, the Middle East, Central Asia, and a small area of Eastern Europe. Antelopes do ...
, zebra,
water buffalo The water buffalo (''Bubalus bubalis''), also called domestic water buffalo, Asian water buffalo and Asiatic water buffalo, is a large bovid originating in the Indian subcontinent and Southeast Asia. Today, it is also kept in Italy, the Balkans ...
and camel, as well as non-mammals, such as crocodile,
emu The emu (; ''Dromaius novaehollandiae'') is a species of flightless bird endemism, endemic to Australia, where it is the Tallest extant birds, tallest native bird. It is the only extant taxon, extant member of the genus ''Dromaius'' and the ...
and ostrich.
Organic farming Organic farming, also known as organic agriculture or ecological farming or biological farming,Labelling, article 30 o''Regulation (EU) 2018/848 of the European Parliament and of the Council of 30 May 2024 on organic production and labelling of ...
supports an increasing demand for meat produced to that standard. File:Lamb meat.jpg, A shoulder of lamb File:Hereford bull large.jpg, A
Hereford Hereford ( ) is a cathedral city and the county town of the ceremonial county of Herefordshire, England. It is on the banks of the River Wye and lies east of the border with Wales, north-west of Gloucester and south-west of Worcester. With ...
bull, a breed of beef cattle File:SelectionOfPackageMeats.jpg, Supermarket meat, North America


Animal growth and development

Several factors affect the growth and development of meat.


Genetics

Some economically important traits in meat animals are heritable to some degree, and can thus be selected for by
animal breeding Animal breeding is a branch of animal science that addresses the evaluation (using best linear unbiased prediction and other methods) of the genetic value (estimated breeding value, EBV) of livestock. Selecting for breeding animals with superior ...
. In cattle, certain growth features are controlled by recessive genes which have not so far been excluded, complicating breeding. One such trait is
dwarfism Dwarfism is a condition of people and animals marked by unusually small size or short stature. In humans, it is sometimes defined as an adult height of less than , regardless of sex; the average adult height among people with dwarfism is . '' ...
; another is the doppelender or " double muscling" condition, which causes
muscle hypertrophy Muscle hypertrophy or muscle building involves a hypertrophy or increase in size of skeletal muscle through a growth in size of its component cells. Two factors contribute to hypertrophy: sarcoplasmic hypertrophy, which focuses more on increa ...
and thereby increases the animal's commercial value.
Genetic analysis Genetic analysis is the overall process of studying and researching in fields of science that involve genetics and molecular biology. There are a number of applications that are developed from this research, and these are also considered parts ...
continues to reveal the mechanisms that control numerous aspects of the
endocrine system The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant Organ (biology), organs. In vertebrat ...
and, through it, meat growth and quality.
Genetic engineering Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of Genetic engineering techniques, technologies used to change the genet ...
can shorten breeding programs significantly because they allow for the identification and isolation of
gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
s coding for desired traits, and for the reincorporation of these genes into the animal
genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...
. To enable this, the genomes of many animals are being mapped. Some research has already seen commercial application. For instance, a recombinant
bacterium Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the ...
has been developed which improves the digestion of grass in the
rumen The rumen, also known as a paunch, is the largest stomach compartment in ruminants. The rumen and the reticulum make up the reticulorumen in ruminant animals. The diverse microbial communities in the rumen allows it to serve as the primary si ...
of cattle, and some features of muscle fibers have been genetically altered. Experimental
reproductive cloning Cloning is the process of producing individual organisms with identical genomes, either by natural or artificial means. In nature, some organisms produce clones through asexual reproduction; this reproduction of an organism by itself without ...
of commercially important meat animals such as sheep, pig or cattle has been successful. Asexual reproduction of animals bearing desirable traits is anticipated.


Environment

Heat regulation in livestock is of economic significance, as mammals attempt to maintain a constant optimal body temperature. Low temperatures tend to prolong animal development and high temperatures tend to delay it. Depending on their size, body shape and insulation through tissue and fur, some animals have a relatively narrow zone of temperature tolerance and others (e.g. cattle) a broad one. Static
magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...
s, for reasons still unknown, retard animal development.


Animal nutrition

The quality and quantity of usable meat depends on the animal's ''plane of nutrition'', i.e., whether it is over- or underfed. Scientists disagree about how exactly the plane of nutrition influences carcase composition. The composition of the diet, especially the amount of protein provided, is an important factor regulating animal growth.
Ruminant Ruminants are herbivorous grazing or browsing artiodactyls belonging to the suborder Ruminantia that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microb ...
s, which may digest
cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...
, are better adapted to poor-quality diets, but their ruminal microorganisms degrade high-quality protein if supplied in excess. Because producing high-quality protein animal feed is expensive, several techniques are employed or experimented with to ensure maximum utilization of protein. These include the treatment of feed with
formalin Formaldehyde ( , ) (systematic name methanal) is an organic compound with the chemical formula and structure , more precisely . The compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde. It is stored as ...
to protect
amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...
s during their passage through the
rumen The rumen, also known as a paunch, is the largest stomach compartment in ruminants. The rumen and the reticulum make up the reticulorumen in ruminant animals. The diverse microbial communities in the rumen allows it to serve as the primary si ...
, the recycling of
manure Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of animal feces; other sources include compost and green manure. Manures contribute to the fertility of soil by adding organic matter and nut ...
by feeding it back to cattle mixed with feed concentrates, or the conversion of petroleum
hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...
s to protein through microbial action. In plant feed, environmental factors influence the availability of crucial
nutrient A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...
s or
micronutrient Micronutrients are essential chemicals required by organisms in small quantities to perform various biogeochemical processes and regulate physiological functions of cells and organs. By enabling these processes, micronutrients support the heal ...
s, a lack or excess of which can cause a great many ailments. In Australia, where the soil contains limited
phosphate Phosphates are the naturally occurring form of the element phosphorus. In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthop ...
, cattle are fed additional phosphate to increase the efficiency of beef production. Also in Australia, cattle and sheep in certain areas were often found losing their appetite and dying in the midst of rich pasture; this was found to be a result of
cobalt Cobalt is a chemical element; it has Symbol (chemistry), symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. ...
deficiency in the soil. Plant
toxin A toxin is a naturally occurring poison produced by metabolic activities of living cells or organisms. They occur especially as proteins, often conjugated. The term was first used by organic chemist Ludwig Brieger (1849–1919), derived ...
s are a risk to grazing animals; for instance,
sodium fluoroacetate Sodium fluoroacetate, also known by its trade name as a mammal poison compound 1080, is an organofluorine chemical compound with the chemical formula . It is the sodium salt of fluoroacetic acid, and contains sodium cations and fluoroacetate ...
, found in some African and Australian plants, kills by disrupting the cellular metabolism. Some man-made
pollutant A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effect, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like oi ...
s such as
methylmercury Methylmercury is an organometallic cation with the formula . It is the simplest organomercury compound. Methylmercury is extremely toxic, and its derivatives are the major source of organic mercury for humans. It is a bioaccumulative environment ...
and some
pesticide Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...
residues present a particular hazard as they
bioaccumulate Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance faster than it can be lost or eliminated by catabolism and excretion. Th ...
in meat, potentially poisoning consumers.


Animal welfare

Practices such as confinement in
factory farming Intensive animal farming, industrial livestock production, and macro-farms, also known as factory farming, is a type of intensive agriculture, specifically an approach to mass animal husbandry designed to maximize production while minimizing co ...
have generated concerns for
animal welfare Animal welfare is the quality of life and overall well-being of animals. Formal standards of animal welfare vary between contexts, but are debated mostly by animal welfare groups, legislators, and academics. Animal welfare science uses measures ...
. Animals have abnormal behaviors such as tail-biting, cannibalism, and
feather pecking Feather pecking is a behavior that occurs most frequently amongst domestic hens reared for egg production,Huber-Eicher, B. and Sebo, F. 2001. The prevalence of feather pecking and development in commercial flocks of laying hens. Applied Animal Be ...
. Invasive procedures such as beak trimming,
castration Castration is any action, surgery, surgical, chemical substance, chemical, or otherwise, by which a male loses use of the testicles: the male gonad. Surgical castration is bilateral orchiectomy (excision of both testicles), while chemical cas ...
, and ear notching have similarly been questioned. Breeding for high productivity may affect welfare, as when
broiler Breed broiler is any chicken (''Gallus gallus domesticus'') that is bred and raised specifically for meat production. Most commercial broilers reach slaughter weight between four and six weeks of age, although slower growing breeds reach slaug ...
chickens are bred to be very large and to grow rapidly. Broilers often have leg deformities and become lame, and many die from the stress of handling and transport.


Human intervention

Meat producers may seek to improve the
fertility Fertility in colloquial terms refers the ability to have offspring. In demographic contexts, fertility refers to the actual production of offspring, rather than the physical capability to reproduce, which is termed fecundity. The fertility rate ...
of female animals through the administration of gonadotrophic or
ovulation Ovulation is an important part of the menstrual cycle in female vertebrates where the egg cells are released from the ovaries as part of the ovarian cycle. In female humans ovulation typically occurs near the midpoint in the menstrual cycle and ...
-inducing
hormone A hormone (from the Ancient Greek, Greek participle , "setting in motion") is a class of cell signaling, signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physio ...
s. In pig production, sow infertility is a common problem – possibly due to excessive fatness. No methods currently exist to augment the fertility of male animals.
Artificial insemination Artificial insemination is the deliberate introduction of sperm into a female's cervix or uterine cavity for the purpose of achieving a pregnancy through in vivo fertilization by means other than sexual intercourse. It is a fertility treatment ...
is now routinely used to produce animals of the best possible genetic quality, and the efficiency of this method is improved through the administration of hormones that synchronize the ovulation cycles within groups of females.
Growth hormone Growth hormone (GH) or somatotropin, also known as human growth hormone (hGH or HGH) in its human form, is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It is thus important in ...
s, particularly
anabolic Anabolism () is the set of metabolic pathways that construct macromolecules like DNA or RNA from smaller units. These reactions require energy, known also as an endergonic process. Anabolism is the building-up aspect of metabolism, whereas catab ...
agents such as
steroid A steroid is an organic compound with four fused compound, fused rings (designated A, B, C, and D) arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes t ...
s, are used in some countries to accelerate muscle growth in animals. This practice has given rise to the beef hormone controversy, an international trade dispute. It may decrease the tenderness of meat, although research on this is inconclusive, and have other effects on the composition of the muscle flesh. Where
castration Castration is any action, surgery, surgical, chemical substance, chemical, or otherwise, by which a male loses use of the testicles: the male gonad. Surgical castration is bilateral orchiectomy (excision of both testicles), while chemical cas ...
is used to improve control over male animals, its side effects can be counteracted by the administration of hormones. Myostatin has been used to produce
muscle hypertrophy Muscle hypertrophy or muscle building involves a hypertrophy or increase in size of skeletal muscle through a growth in size of its component cells. Two factors contribute to hypertrophy: sarcoplasmic hypertrophy, which focuses more on increa ...
.
Sedative A sedative or tranquilliser is a substance that induces sedation by reducing irritability or Psychomotor agitation, excitement. They are central nervous system (CNS) Depressant, depressants and interact with brain activity, causing its decelera ...
s may be administered to animals to counteract stress factors and increase weight gain. The feeding of
antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...
to certain animals increases growth rates. This practice is particularly prevalent in the US, but has been banned in the EU, partly because it causes
antimicrobial resistance Antimicrobial resistance (AMR or AR) occurs when microbes evolve mechanisms that protect them from antimicrobials, which are drugs used to treat infections. This resistance affects all classes of microbes, including bacteria (antibiotic resista ...
in
pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...
ic microorganisms.


Composition


Biochemical

The biochemical composition of meat varies in complex ways depending on the species, breed, sex, age, plane of nutrition, training and exercise of the animal, as well as on the anatomical location of the musculature involved. Even between animals of the same litter and sex there are considerable differences in such parameters as the percentage of intramuscular fat. Adult mammalian
muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...
consists of roughly 75 percent water, 19 percent protein, 2.5 percent intramuscular fat, 1.2 percent
carbohydrate A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ...
s and 2.3 percent other soluble substances. These include organic compounds, especially
amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...
s, and inorganic substances such as minerals. Muscle proteins are either soluble in water (
sarcoplasm Sarcoplasm is the cytoplasm of a muscle cell. It is comparable to the cytoplasm of other cells, but it contains unusually large amounts of glycogen (a polymer of glucose), myoglobin, a red-colored protein necessary for binding oxygen molecules tha ...
ic proteins, about 11.5 percent of total muscle mass) or in concentrated salt solutions (
myofibril A myofibril (also known as a muscle fibril or sarcostyle) is a basic rod-like organelle of a muscle cell. Skeletal muscles are composed of long, tubular cells known as Skeletal muscle#Skeletal muscle cells, muscle fibers, and these cells contain ...
lar proteins, about 5.5 percent of mass). There are several hundred sarcoplasmic proteins. Most of them – the glycolytic
enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...
s – are involved in
glycolysis Glycolysis is the metabolic pathway that converts glucose () into pyruvic acid, pyruvate and, in most organisms, occurs in the liquid part of cells (the cytosol). The Thermodynamic free energy, free energy released in this process is used to form ...
, the conversion of sugars into high-energy molecules, especially
adenosine triphosphate Adenosine triphosphate (ATP) is a nucleoside triphosphate that provides energy to drive and support many processes in living cell (biology), cells, such as muscle contraction, nerve impulse propagation, and chemical synthesis. Found in all known ...
(ATP). The two most abundant myofibrillar proteins,
myosin Myosins () are a Protein family, family of motor proteins (though most often protein complexes) best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes. They are adenosine triphosphate, ATP- ...
and
actin Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of ...
, form the muscle's overall structure and enable it to deliver power, consuming ATP in the process. The remaining protein mass includes
connective tissue Connective tissue is one of the four primary types of animal tissue, a group of cells that are similar in structure, along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesod ...
(
collagen Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...
and
elastin Elastin is a protein encoded by the ''ELN'' gene in humans and several other animals. Elastin is a key component in the extracellular matrix of gnathostomes (jawed vertebrates). It is highly Elasticity (physics), elastic and present in connective ...
). Fat in meat can be either
adipose tissue Adipose tissue (also known as body fat or simply fat) is a loose connective tissue composed mostly of adipocytes. It also contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, Blood vessel, vascular endothel ...
, used by the animal to store energy and consisting of "true fats" (
ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...
s of
glycerol Glycerol () is a simple triol compound. It is a colorless, odorless, sweet-tasting, viscous liquid. The glycerol backbone is found in lipids known as glycerides. It is also widely used as a sweetener in the food industry and as a humectant in pha ...
with
fatty acid In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...
s), or intramuscular fat, which contains
phospholipid Phospholipids are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typ ...
s and
cholesterol Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils. Cholesterol is biosynthesis, biosynthesized by all anima ...
. Meat can be broadly classified as "red" or "white" depending on the concentration of
myoglobin Myoglobin (symbol Mb or MB) is an iron- and oxygen-binding protein found in the cardiac and skeletal muscle, skeletal Muscle, muscle tissue of vertebrates in general and in almost all mammals. Myoglobin is distantly related to hemoglobin. Compar ...
in muscle fiber. When myoglobin is exposed to
oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
, reddish oxymyoglobin develops, making myoglobin-rich meat appear red. The redness of meat depends on species, animal age, and fiber type:
Red meat In gastronomy, red meat is commonly red when raw (and a dark color after it is cooked), in contrast to white meat, which is pale in color before (and after) cooking. In culinary terms, only flesh from mammals or fowl (not fish) is classified ...
contains more narrow muscle fibers that tend to operate over long periods without rest, while white meat contains more broad fibers that tend to work in short fast bursts, such as the brief flight of the chicken. The meat of adult mammals such as
cows Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are called co ...
,
sheep Sheep (: sheep) or domestic sheep (''Ovis aries'') are a domesticated, ruminant mammal typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to d ...
, and
horses The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 milli ...
is considered red, while
chicken The chicken (''Gallus gallus domesticus'') is a domesticated subspecies of the red junglefowl (''Gallus gallus''), originally native to Southeast Asia. It was first domesticated around 8,000 years ago and is now one of the most common and w ...
and
turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...
breast meat is considered white. File:Blade steak (cropped).jpg, "Red" meat:
beef steak File:Hühnerbrustfilet 20090502 001 (cropped).JPG, "White" meat:
chicken breast (flight muscle)


Nutritional

Muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...
tissue is high in protein, containing all of the
essential amino acid An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life forms ...
s, and in most cases is a good source of
zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...
, vitamin B12,
selenium Selenium is a chemical element; it has symbol (chemistry), symbol Se and atomic number 34. It has various physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elem ...
,
phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...
,
niacin Nicotinic acid, or niacin, is an organic compound and a vitamer of vitamin B3, an essential human nutrient. It is produced by plants and animals from the amino acid tryptophan. Nicotinic acid is also a prescription medication. Amounts f ...
, vitamin B6,
choline Choline is a cation with the chemical formula . Choline forms various Salt (chemistry), salts, such as choline chloride and choline bitartrate. An essential nutrient for animals, it is a structural component of phospholipids and cell membrane ...
,
riboflavin Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide. These coenzymes are involved in ...
and iron. Several forms of meat are high in
vitamin K Vitamin K is a family of structurally similar, fat-soluble vitamers found in foods and marketed as dietary supplements. The human body requires vitamin K for post-translational modification, post-synthesis modification of certain proteins ...
. Muscle tissue is very low in carbohydrates and does not contain dietary fiber. The fat content of meat varies widely with the
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
and
breed A breed is a specific group of breedable domestic animals having homogeneous appearance (phenotype), homogeneous behavior, and/or other characteristics that distinguish it from other organisms of the same species. In literature, there exist seve ...
of animal, the way in which the animal was raised, what it was fed, the part of the body, and the methods of butchering and cooking. Wild animals such as
deer A deer (: deer) or true deer is a hoofed ruminant ungulate of the family Cervidae (informally the deer family). Cervidae is divided into subfamilies Cervinae (which includes, among others, muntjac, elk (wapiti), red deer, and fallow deer) ...
are leaner than farm animals, leading those concerned about fat content to choose
game A game is a structured type of play usually undertaken for entertainment or fun, and sometimes used as an educational tool. Many games are also considered to be work (such as professional players of spectator sports or video games) or art ...
such as
venison Venison refers primarily to the meat of deer (or antelope in South Africa). Venison can be used to refer to any part of the animal, so long as it is edible, including the internal organs. Venison, much like beef or pork, is categorized into spe ...
. Decades of breeding meat animals for fatness is being reversed by consumer demand for leaner meat. The fatty deposits near the muscle fibers in meats soften meat when it is cooked, improve its flavor, and make the meat seem juicier. Fat around meat further contains
cholesterol Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils. Cholesterol is biosynthesis, biosynthesized by all anima ...
. The increase in meat consumption after 1960 is associated with significant imbalances of fat and cholesterol in the human diet.


Production

File:World production of meat, main items.svg, World production of meat, main items File:World production of main meat items, main producers (2019).svg, World production of main meat items, main producers (2019)


Transport

Upon reaching a predetermined age or weight, livestock are usually transported ''en masse'' to the slaughterhouse. Depending on its length and circumstances, this may exert stress and injuries on the animals, and some may die ''en route''. Unnecessary stress in transport may adversely affect the quality of the meat. In particular, the muscles of stressed animals are low in water and
glycogen Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. It is the main storage form of glucose in the human body. Glycogen functions as one of three regularly used forms ...
, and their pH fails to attain acidic values, all of which results in poor meat quality.


Slaughter

Animals are usually slaughtered by being first stunned and then exsanguinated (bled out). Death results from the one or the other procedure, depending on the methods employed. Stunning can be effected through
asphyxia Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects all the tissues and organs, some more rapidly than others. There are m ...
ting the animals with
carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
, shooting them with a gun or a captive bolt pistol, or shocking them with electric current. The exsanguination is accomplished by severing the carotid artery and the jugular vein in cattle and sheep, and the anterior vena cava in pigs. Draining as much blood as possible from the carcass is necessary because blood causes the meat to have an unappealing appearance and is a breeding ground for microorganisms.


Dressing and cutting

After exsanguination, the carcass is dressed; that is, the head, feet, hide (except hogs and some veal), excess fat, viscera and
offal Offal (), also called variety meats, pluck or organ meats, is the internal organ (anatomy), organs of a butchered animal. Offal may also refer to the by-products of Milling (grinding), milled grains, such as corn or wheat. Some cultures strong ...
are removed, leaving only bones and edible muscle. Cattle and pig carcases, but not those of sheep, are then split in half along the mid ventral axis, and the carcase is cut into wholesale pieces. The dressing and cutting sequence, long a province of manual labor, is being progressively automated.


Conditioning

Under hygienic conditions and without other treatment, meat can be stored at above its freezing point (−1.5 °C) for about six weeks without spoilage, during which time it undergoes an aging process that increases its tenderness and flavor. During the first day after death,
glycolysis Glycolysis is the metabolic pathway that converts glucose () into pyruvic acid, pyruvate and, in most organisms, occurs in the liquid part of cells (the cytosol). The Thermodynamic free energy, free energy released in this process is used to form ...
continues until the accumulation of lactic acid causes the pH to reach about 5.5. The remaining
glycogen Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. It is the main storage form of glucose in the human body. Glycogen functions as one of three regularly used forms ...
, about 18 g per kg, increases the water-holding capacity and tenderness of cooked meat. ''Rigor mortis'' sets in a few hours after death as
adenosine triphosphate Adenosine triphosphate (ATP) is a nucleoside triphosphate that provides energy to drive and support many processes in living cell (biology), cells, such as muscle contraction, nerve impulse propagation, and chemical synthesis. Found in all known ...
is used up. This causes the muscle proteins
actin Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of ...
and
myosin Myosins () are a Protein family, family of motor proteins (though most often protein complexes) best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes. They are adenosine triphosphate, ATP- ...
to combine into rigid actomyosin. This in turn lowers the meat's water-holding capacity, so the meat loses water or "weeps". In muscles that enter ''rigor'' in a contracted position, actin and myosin filaments overlap and cross-bond, resulting in meat that becomes tough when cooked. Over time, muscle proteins Denaturation (biochemistry), denature in varying degree, with the exception of the collagen and
elastin Elastin is a protein encoded by the ''ELN'' gene in humans and several other animals. Elastin is a key component in the extracellular matrix of gnathostomes (jawed vertebrates). It is highly Elasticity (physics), elastic and present in connective ...
of
connective tissue Connective tissue is one of the four primary types of animal tissue, a group of cells that are similar in structure, along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesod ...
, and ''rigor mortis'' resolves. These changes mean that meat is tender and pliable when cooked just after death or after the resolution of ''rigor'', but tough when cooked during ''rigor.'' As the muscle pigment
myoglobin Myoglobin (symbol Mb or MB) is an iron- and oxygen-binding protein found in the cardiac and skeletal muscle, skeletal Muscle, muscle tissue of vertebrates in general and in almost all mammals. Myoglobin is distantly related to hemoglobin. Compar ...
denatures, its iron oxidation, oxidizes, which may cause a brown discoloration near the surface of the meat. Ongoing proteolysis contributes to conditioning: hypoxanthine, a breakdown product of ATP, contributes to meat's flavor and odor, as do other products of the decomposition of muscle fat and protein. File:Atria slaughterhouse in Nurmo Seinajoki.JPG, A slaughterhouse, Finland File:MIN Rungis viandes de boucherie veau.jpg, Marché d'Intérêt National de Rungis, Rungis International Market, France File:Sucuk-1.jpg, The word "sausage" is derived from Old French , from Latin , "salted".


Additives

When meat is industrially processed, Food additive, additives are used to protect or modify its flavor or color, to improve its tenderness, juiciness or cohesiveness, or to aid with its Meat preservation, preservation.


Consumption


Historical

A Bioarchaeology, bioarchaeological (specifically, isotopic analysis) study of early medieval England found, based on the funerary record, that high-meat protein diets were extremely rare, and that (contrary to previously held assumptions) elites did not consume more meat than non-elites, and men did not consume more meat than women. In the nineteenth century, meat consumption in Britain was the highest in Europe, exceeded only by that in British colonies. In the 1830s consumption per head in Britain was about a year, rising to in 1912. In 1904, laborers consumed a year while aristocrats ate . There were some 43,000 butcher's shops in Britain in 1910, with "possibly more money invested in the meat industry than in any other British business" except finance. The US was a meat importing country by 1926. Truncated lifespan as a result of intensive breeding allows more meat to be produced from fewer animals. The world cattle population was about 600 million in 1929, with 700 million sheep and goats and 300 million pigs.


Trends

According to the Food and Agriculture Organization, the overall consumption for #Red and white meat, white meat has increased from the 20th to the 21st centuries. Poultry meat has increased by 76.6% per kilo per capita and pig meat by 19.7%. Bovine meat has decreased from per capita in 1990 to per capita in 2009. FAO analysis found that 357 million tonnes of meat were produced in 2021, 53% more than in 2000, with chicken meat representing more than half the increase. Overall, diets that include meat are the most common worldwide according to the results of a 2018 Ipsos MORI study of 16–64 years olds in 28 countries. Ipsos states "An omnivorous diet is the most common diet globally, with non-meat diets (which can include fish) followed by over a tenth of the global population." Approximately 87% of people include meat in their diet in some frequency. 73% of meat eaters included it in their diet regularly and 14% consumed meat only occasionally or infrequently. The type of meat consumed varies between different cultures. The amount and kind of meat consumed varies by income, both between countries and within a given country. horse meat, Horses are commonly eaten in countries such as France, Italy, Germany and Japan. Horses and other large
mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
s such as reindeer were hunted during the late Paleolithic in western Europe. dog meat, Dogs are consumed in China, South Korea and Vietnam. Dogs are occasionally eaten in the Arctic regions. Historically, dog meat has been consumed in various parts of the world, such as Hawaii, Japan, Switzerland and Mexico. cat meat, Cats are sometimes eaten, such as in Peru. Guinea pigs are raised for their flesh in the Andes. Whales and dolphins are hunted, partly for their flesh, in several countries. Misidentification is a risk; in 2013, products in Europe labelled as beef 2013 meat adulteration scandal, actually contained horse meat.


Methods of preparation

Meat can be cooked in many ways, including braise, braising, broiling, frying, grilling, and
roasting Roasting is a cooking method that uses dry heat where hot air covers the food, cooking it evenly on all sides with temperatures of at least from an open flame, oven, or other heat source. Roasting can enhance the flavor through caramelizat ...
. Meat can be curing (food preservation), cured by smoking (food), smoking, which preserves and flavors food by exposing it to smoke from burning or smoldering wood. Other methods of curing include pickling, salted meat, salting, and air-drying. Some recipes call for raw meat; steak tartare is made from minced raw beef. Pâtés are made with ground meat and fat, often including
liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...
. File:Janjetina i odojak na ražnju u Novalji.2 (cropped).jpg , Spit-roasting a lamb and a suckling pig File:Копчіння тушок гусей.jpg , Geese being smokehouse, smoked in a smokehouse File:Papaz yahnisi - cooking.jpg , Stewing mutton with vegetables File:Pan frying sausages.jpg , Frying pork sausages in a pan File:Steak Tartare in Dresden.jpg , Raw beef: steak tartare File:Duck Liver Pâté.jpg , Duck liver pâté


Health effects

Meat, in particular red and processed meat, is linked to a variety of health risks. The ''2015–2020 Dietary Guidelines for Americans'' asked men and teenage boys to increase their consumption of vegetables or other underconsumed foods (fruits, whole grains, and dairy) while reducing intake of protein foods (meats, poultry, and eggs) that they currently overconsume.


Contamination

Toxic compounds including heavy metals, mycotoxins,
pesticide Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...
residues, Polychlorinated dibenzodioxins, dioxins, polychlorinated biphenyl can contaminate meat. Processed, smoked and cooked meat may contain carcinogens such as polycyclic aromatic hydrocarbons. Toxins may be introduced to meat as part of animal feed, as veterinary drug residues, or during processing and cooking. Such compounds are often metabolized in the body to form harmful by-products. Negative effects depend on the individual genome, diet, and history of the consumer.


Cancer

The consumption of processed and red meat carries an increased risk of cancer. The International Agency for Research on Cancer (IARC), a specialized agency of the World Health Organization (WHO), classified processed meat (e.g., bacon, ham, hot dogs, sausages) as, "carcinogenic to humans (Group 1), based on sufficient evidence in humans that the consumption of processed meat causes colorectal cancer." IARC classified red meat as "probably carcinogenic to humans (Group 2A), based on limited evidence that the consumption of red meat causes cancer in humans and strong mechanistic evidence supporting a carcinogenic effect." Cancer Research UK, National Health Service (NHS) and the National Cancer Institute have stated that red and processed meat intake increases risk of bowel cancer. The American Cancer Society in their "Diet and Physical Activity Guideline", stated "evidence that red and processed meats increase cancer risk has existed for decades, and many health organizations recommend limiting or avoiding these foods." The Canadian Cancer Society have stated that "eating red and processed meat increases cancer risk". A 2021 review found an increase of 11–51% risk of multiple cancer per 100g/d increment of red meat, and an increase of 8–72% risk of multiple cancer per 50g/d increment of processed meat. Cooking muscle meat creates heterocyclic amines (HCAs), which are thought to increase cancer risk in humans. Researchers at the National Cancer Institute published results of a study which found that human subjects who ate beef rare or medium-rare had less than one third the risk of stomach cancer than those who ate beef medium-well or well-done. While eating muscle meat raw may be the only way to avoid HCAs fully, the National Cancer Institute states that cooking meat below creates "negligible amounts" of HCAs. Microwaving meat before cooking may reduce HCAs by 90%. Nitrosamines, present in processed and cooked foods, are carcinogenic, being linked to colon cancer. Polycyclic aromatic hydrocarbons, present in processed, smoked and cooked foods, are similarly carcinogenic.


Bacterial contamination

Bacterial contamination has been seen with meat products. A 2011 study by the Translational Genomics Research Institute showed that nearly half (47%) of the meat and poultry in U.S. grocery stores were contaminated with ''Staphylococcus aureus, S. aureus'', with more than half (52%) of those bacteria resistant to antibiotics. A 2018 investigation by the Bureau of Investigative Journalism and ''The Guardian'' found that around 15 percent of the US population suffers from foodborne illnesses every year. The investigation highlighted unsanitary conditions in US-based meat plants, which included meat products covered in excrement and abscesses "filled with pus". Complete cooking and the careful avoidance of recontamination reduce the risk of bacterial infections from meat.


Diabetes

Consumption of 100 g/day of red meat and 50 g/day of processed meat is associated with an increased risk of
diabetes Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...
. Diabetes UK advises people to limit their intake of red and processed meat.


Infectious diseases

Meat production and trade substantially increase risks for infectious diseases (zoonosis), including pandemic prevention, of pandemics, whether though contact with wild and farmed animals, or via husbandry's environmental impact. For example, avian influenza from poultry meat production is a threat to human health. Furthermore, the use of antibiotics in meat production contributes to
antimicrobial resistance Antimicrobial resistance (AMR or AR) occurs when microbes evolve mechanisms that protect them from antimicrobials, which are drugs used to treat infections. This resistance affects all classes of microbes, including bacteria (antibiotic resista ...
– which contributes to millions of deaths – and makes it harder to control infectious diseases.


Changes in consumer behavior

In response to changing meat prices as well as health concerns about lipid hypothesis, saturated fat and cholesterol, consumers have altered their consumption of various meats. Consumption of beef in the United States between 1970 and 1974 and 1990–1994 dropped by 21%, while consumption of Chicken (food), chicken increased by 90%.


Heart disease

Except for poultry, at 50 g/day unprocessed red and processed meat are risk factors for ischemic heart disease, increasing the risk by about 9 and 18% respectively.


Environmental impact

A multitude of serious negative environmental effects are associated with meat production. Among these are greenhouse gas emissions, fossil energy use, water use, water quality changes, and effects on grazed ecosystems. They are so significant that according to University of Oxford researchers, "a Veganism, vegan diet is probably the single biggest way to reduce your impact on planet Earth... far bigger than cutting down on your flights or buying an electric car". However, this is often ignored in the public consciousness and in plans to tackle serious environmental issues such as the climate crisis. The livestock sector may be the largest source of water pollution (due to animal wastes, fertilizers, pesticides), and it contributes to emergence of antibiotic resistance. It accounts for over 8% of global human water use. It is a significant driver of Holocene extinction, biodiversity loss and ecosystems, as it causes deforestation, ocean Dead zone (ecology), dead zones, species extinction, land degradation, pollution, overfishing and
global warming Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...
. Cattle farming was estimated to be responsible for 80 per cent of Amazon deforestation in 2008 due to the clearing of forests to grow animal feed (especially soya) and cattle ranching. Environmental effects vary among livestock production systems. Grazing of livestock can be beneficial for some wildlife species, but not for others. Targeted grazing of livestock is used as a food-producing alternative to herbicide use in some vegetation management.


Land use

Meat production is by far the biggest user of land, as it accounts for nearly 40% of the global land surface. Just in the contiguous United States, 34% of its land area () are used as pasture and rangeland, mostly feeding livestock, not counting of cropland (20%), some of which is used for producing feed for livestock. Roughly 75% of Deforestation, deforested land around the globe is used for livestock pasture. Deforestation from practices like slash-and-burn releases and removes the carbon sink of grown tropical forest ecosystems which substantially mitigate climate change. Land use is a major pressure on pressure on Soil conservation, fertile soils which is important for global food security.


Climate change

The rising global consumption of emission intensity, carbon-intensive meat products has "exploded the global carbon footprint of agriculture," according to some top scientists. Meat production is responsible for some 35% of global emissions of greenhouse gases, and 60% of the greenhouse gases attributable to food production. Some nations show very different impacts to counterparts within the same group, with Brazil and Australia having emissions over 200% higher than the average of their respective income groups, driven by meat consumption. According to the ''Assessing the Environmental Impacts of Consumption and Production'' report produced by United Nations Environment Programme's (UNEP) international panel for sustainable resource management, a worldwide transition in the direction of a meat and dairy free diet is indispensable if adverse global climate change were to be prevented. A 2019 report in ''The Lancet'' recommended that global meat (and sugar) consumption be reduced by 50 percent to Climate change mitigation, mitigate climate change. Meat consumption in Western societies needs to be reduced by up to 90% according to a 2018 study published in ''Nature (journal), Nature''. The 2019 special report by the Intergovernmental Panel on Climate Change called for significantly reducing meat consumption, particularly in wealthy countries, in order to mitigate and adapt to climate change.


Biodiversity loss

Meat consumption is a primary contributor to the Holocene extinction, sixth mass extinction. A 2017 study by the World Wildlife Fund found that 60% of global
biodiversity loss Biodiversity loss happens when plant or animal species disappear completely from Earth (extinction) or when there is a decrease or disappearance of species in a specific area. Biodiversity loss means that there is a reduction in Biodiversity, b ...
is attributable to meat-based diets, in particular from the use of land for feed crops, resulting in large-scale loss of habitats and species. Livestock make up 60% of the Biomass (ecology), biomass of all mammals on earth, followed by humans (36%) and wild mammals (4%). In November 2017, 15,364 world scientists signed a World Scientists' Warning to Humanity, Warning to Humanity calling for a drastic reduction in per capita consumption of meat and "dietary shifts towards mostly plant-based foods". The 2019 ''Global Assessment Report on Biodiversity and Ecosystem Services'' recommended a reduction in meat consumption to mitigate biodiversity loss. A 2021 Chatham House report asserted that a shift towards plant-based diets would free up land for the restoration of ecosystems and biodiversity. Meat consumption is predicted to rise as the human population increases and becomes more affluent; this in turn would increase greenhouse gas emissions and further reduce biodiversity.


Reducing environmental impact

The environmental impact of meat production can be reduced on the farm by conversion of human-inedible residues of food crops. Manure from meat-producing livestock is used as fertilizer. Substitution of animal manures for synthetic fertilizers in crop production can be environmentally significant, as between 43 and 88 MJ of fossil fuel energy are used per kg of nitrogen in manufacture of synthetic nitrogenous fertilizers.


Reducing meat consumption

The IPCC and others have stated that meat production has to be reduced substantially for any sufficient climate change mitigation, mitigation of climate change and, at least initially, largely through Sustainable consumption#Shifting consumption, shifts towards plant-based diets where meat consumption is high. Personal carbon trading, Personal carbon allowances that rationing, allow a certain amount of free meat consumption per person would be a form of restriction, meat taxes would be a type of fiscal mechanism. Meat can be replaced by, for example, high-protein iron-rich low-emission legumes and common fungi, dietary supplements (e.g. of vitamin B12) and fortified foods, cultured meat, Microbial food cultures, microbial foods, mycoprotein, List of meat substitutes, meat substitutes, and other alternatives, such as those based on mushrooms, legumes (pulses), and other food sources. Land previously used for meat production can be Restoration ecology, rewilded. The biologists Rodolfo Dirzo, Gerardo Ceballos, and Paul R. Ehrlich state that it is the "massive planetary monopoly of industrial meat production that needs to be curbed" while respecting the cultural traditions of indigenous peoples, for whom meat is an important source of protein.


Cultural aspects

Meat is part of the human diet in most cultures, where it often has symbolic meaning and important social functions. Some people choose not to eat meat (vegetarianism) or any food made from animals (veganism). The reasons for not eating all or some meat may include ethical objections to killing animals for food, health concerns, environmental concerns or religious dietary laws.


Ethical issues

Ethical issues regarding the consumption of meat include objecting to the act of killing animals or to the intensive agriculture, agricultural practices used in meat production. Reasons for objecting to killing animals for consumption may include animal rights, environmental ethics, or an aversion to inflicting pain or harm on sentience, sentient animals. Some people, while not vegetarians, refuse to eat the flesh of certain animals for cultural or religious reasons. The founders of Western philosophy disagreed about the ethics of eating meat. Plato's ''Republic (Plato), Republic'' has Socrates describe the ideal state as vegetarian. Pythagoras believed that humans and animals were equal and therefore disapproved of meat consumption, as did Plutarch, whereas Zeno of Elea, Zeno and Epicurus were vegetarian but allowed meat-eating in their philosophy. Conversely, Aristotle's ''Politics (Aristotle), Politics'' assert that animals, as inferior beings, exist to serve humans, including as food. Augustine drew on Aristotle to argue that the universe's natural hierarchy allows humans to eat animals, and animals to eat plants. Age of Enlightenment, Enlightenment philosophers were likewise divided. Descartes wrote that animals were merely animated machines, while Kant considered them inferior beings for lack of discernment: means rather than ends. But Voltaire and Rousseau disagreed; Rousseau argued that meat-eating is a social rather than a natural act, because children are not interested in meat. Later philosophers examined the changing practices of eating meat in the modern age as part of a process of detachment from animals as living beings. Norbert Elias, for instance, noted that in medieval times cooked animals were brought to the table whole, but that since the Renaissance only the edible parts are served, which are no longer recognizably part of an animal. Modern eaters, according to :fr:Noëlie Vialles, Noëlie Vialles, demand an "Ellipsis (linguistics), ellipsis" between meat and dead animals. Fernand Braudel wrote that since the European diet of the 15th and 16th century was particularly heavy in meat, European colonialism helped export meat-eating across the globe, as colonized peoples took up the culinary habits of their colonizers.


Religious traditions

Among the Indian religions, Jainism opposes the eating of meat, while some Buddhist vegetarianism, schools of Buddhism and Hinduism#Vegetarian Hindus, Hinduism advocate but do not mandate vegetarianism. Some Sikhism, Sikh groups oppose eating any meat. Jewish ''Kashrut'' dietary rules allow certain (''kosher'') meat and forbid other (''treif'') meat. Similar rules apply in Islamic dietary laws: The Quran explicitly forbids meat from animals that die naturally, blood, and the meat of pigs, which are ''haram'', forbidden, as opposed to ''halal'', allowed.


Psychology

Research in applied psychology has investigated meat eating in relation to morality, emotions, cognition, and personality. Psychological research suggests meat eating is correlated with masculinity, and reduced Big Five personality traits#Openness to experience, openness to experience. Research into the consumer psychology of meat is relevant both to meat industry marketing and to those advocating eating less meat.


Gender

Unlike most other foods, meat is not perceived as gender-neutral; it is associated with men and masculinity. Sociological research, ranging from African tribal societies to contemporary barbecue, indicates that men are much more likely to participate in preparing meat than other food. This has been attributed to the influence of traditional male gender roles, in view of what Jack Goody calls a "male familiarity with killing", or as Claude Lévi-Strauss suggests, that
roasting Roasting is a cooking method that uses dry heat where hot air covers the food, cooking it evenly on all sides with temperatures of at least from an open flame, oven, or other heat source. Roasting can enhance the flavor through caramelizat ...
(meat) is more violent than boiling (grains and vegetables). In modern societies, men tend to consume more meat than women, and men often prefer red meat whereas women tend to prefer chicken and fish.


See also

* Bushmeat * Culinary name * Cartilage (also called gristle) * List of meat dishes * Meat on the bone * Meat-free days * Mechanically separated meat * Mystery meat


References


Sources

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External links


American Meat Science Association website

IARC Monographs Q&A

IARC Monographs Q&A on the carcinogenicity of the consumption of red meat and processed meat.
{{Authority control Meat, Types of food Meat industry, Agricultural products